1. Field of the Invention
The invention relates to the structure design field of an electronic device, in particular to an optimization design method for a structure, which can be used to guide the optimization design for the chassis structure of an electronic device and the analysis of thermal and electromagnetic compatibility property.
2. Background and Relevant Art
With the rapid development of the electronic industry, the range of application of an electronic device becomes increasingly widely, and an electronic device is present everywhere, not only in a daily life but also in a military field.
An electronic device will be inevitably affected by various external loads such as a vibration, an impact, a centrifugal force and a friction generated from a movement, during the course of transport, storage and use, wherein the vibration and the impact are most harmful. According to statistics, of the environmental factors causing a failure of an airborne electronic device, the vibration factor accounts for 27%, and in the electronic devices used in a modern war, 50%-60% of the failures are due to a mechanical vibration and a explosion impact. The destructive effect is mainly manifested in two aspects: a mechanical damage caused by a vibration impact and the degradation and failure of an electrical performance of a device, which will result in a fatigue failure of an electronic device, a drift of an electrical parameter, a break of a component lead or the peeling off of a solder joint and the loosing of a fastener, etc. It was experimentally found that the vibration causes more damages than the impact does. As the main load-bearing parts, the design of the chassis structure of an electronic device is very important.
There are still problems of electromagnetic compatibility in an electronic device, the electromagnetic compatibility is the ability to work properly in a common electromagnetic environment without being affected by an interference. In practice, the examples of problems resulting from bad electromagnetic compatibility are without number, for example, the civil aviation prohibits passengers from using some specific electronic devices, such as cell phones and the like, in flight. Therefore, an electronic product must get through a certification of electromagnetic compatibility. Electromagnetic compatibility problems exist not only between devices, but also between components, between members, and between systems, or even exist inside an integrated circuit. The main solution is to perform an electromagnetic shielding. For an electrical device, with the chassis as a main shielding structure, openings and apertures on a chassis body and the layout of an internal structure will affect the electromagnetic shielding effectiveness of an electronic device.
Meanwhile, there are many electronic components inside an electronic device, with the increase of integration of electronic components, the heat generation also increases, in order to ensure the proper work of the components, the temperature inside the chassis of the electronic device must be controlled, and a heat dissipation treatment is required. Because the reliability of electronic components is extremely sensitive to the temperature, the reliability will be decreased by 5% with the device temperature increasing every one degree Celsius at 70-80 degrees Celsius. A volume of the electronic device needs to be controlled, which is especially a fact for a military electronic device, which results in a great difficulty for the heat dissipation. Thus a thermal design of the chassis of the electronic device is also very critical.
The chassis of an electronic device is to combine a variety of electronic components or mechanical parts inside the electronic device as a whole, and to avoid or decrease the effects on electrical performance due to an adverse factor such as a high or low temperature, a vibration impact, an electromagnetic interference. An electronic device structure is designed to provide the internal electronic components and assemblies with a good micro-environment able to resist harsh conditions outside, an anti-vibration buffer design, a thermal control design and an electromagnetic compatibility design is one of key technologies thereof. Multi-field coupling of an electronic device thus becomes the focus of a research and design.
For the structure design of the chassis of this type of electronic device, in the present, usually the structure design is made first, and then a thermal analysis and an electromagnetic compatibility analysis, the structure design is reasonable if meeting the relevant requirements; otherwise the structure design is modified, the thermal analysis and the electromagnetic compatibility analysis are performed again. During this design flow, the three separate disciplines are clearly independent each other, resulting in a long design cycle, difficulties for an product meeting the requirements of the three aspects of mechanical, electrical and thermal aspects simultaneously. A lot of researches have been done by foreign and domestic scholars with respect to the multi-field coupling problem, but mostly are restricted to a particular engineering field, do not have a broad applicability, and the research of the multi-field coupling problem with respect to the chassis structure and the like of electronic devices is still very rare.